1. Field of the Invention
The invention is related to a sensing technology for sensing an electric fuse and in particular related to a technology for sensing a state of the electric fuse according to a discharging speed of a capacitor.
2. Description of Related Art
FIG. 1 is a diagram depicting a sensing circuit of a conventional electric fuse. Referring to FIG. 1, a sensing circuit 10 includes inverters 101˜104, transistors 105˜111, switches 112 and 113, constant current sources 114 and 115, and a resistance 116. Signals sense and sense_have opposite phases.
The sensing circuit 10 utilizes the constant current sources 114 and 115 to generate voltages Vefuse and Vref. The electric fuse 117 has a high resistance value before being programmed, and the voltage Vefuse is higher than the voltage Vref. Thus, a signal Fsout has a high-logic level. The electric fuse 117 has a low resistance value after being programmed, and the voltage Vefuse is lower than the voltage Vref. Thus, the signal Fsout has a low-logic level. That is, the signal Fsout is an indication of whether the electric fuse 117 is programmed.